Mixtures of nonionic ethers for use as rinse aids and/or cleaning hard surfaces

ABSTRACT

A rinse aid composition for hard surfaces containing 
     a) mixed ethers corresponding to formula (I) ##STR1##  in which R 1  is a linear or branched, aliphatic alkyl or alkenyl radical containing 8 to 18 carbon atoms, R 2  is a linear or branched alkyl radical containing 1 to 4 carbon atoms or a benzyl radical, m1 has a value of 0 or 1 to 2 and n1 has a value of 5 to 15, and 
     b) fatty alcohol polypropylene glycol/polyethylene glycol ethers corresponding to formula (II) ##STR2##  in which R 3  is a linear or branched, aliphatic alkyl or alkenyl radical containing 8 to 16 carbon atoms, m2 has a value of 0 or 1 to 3 and n2 has a value of 1 to 5.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to new formulations for the machine cleaning ofhard surfaces, more particularly rinse aids, containing mixed ethers andspecial fatty alcohol polyglycol ethers and to the use of these mixturesfor the production of the new formulations.

2. Discussion of Related Art

Commercial rinse aids are mixtures of low-foaming fatty alcoholpolyethylene/polypropylene glycol ethers, solubilizers (for examplecumene sulfonate), organic acids (for example citric acid) and solvents(for example ethanol). The function of rinse aids is to influence theinterfacial tension of the water in such a way that it is able to drainfrom the rinsed surfaces in the form of a thin coherent film, so that nowater droplets, streaks or films are left after the subsequent dryingprocess. A review of the composition of rinse aids and methods fortesting their performance is presented by W. Schirmer et al. in Tens.Surf. Det. 28, 313 (1991).

In addition, where modern phosphate-free, low-alkali detergents are usedfor machine dishwashing, lime and silicate coatings can form on therinsed surfaces and on the inside of the interior of the dishwashingmachine because the calcium binding capacity of these detergents islower than that of conventional phosphate-containing products.Troublesome lime or silicate coatings occur in particular when therinsing water of the dishwashing machine has not been softenedsufficiently, if at all, and exceeds a hardness of 4° d. In cases suchas these, lime silicate coatings can be effectively avoided if citricacid is introduced into the final rinse cycle through the rinse aid.However, since the quantities of rinse aid normally added during thefinal rinse cycle are very small, i.e. 3 ml to 6 ml, the citric acidcontent of rinse aid formulations designed to guarantee effectiveinhibition of coatings has to be relatively high to achieve an adequateacid or complexing capacity. High citric acid contents support theeffect of the phosphate substitutes and guarantee spotless crockery.

EP-B1 0 197 434 (Henkel) describes rinse aids which contain mixed ethersas surfactants. Various materials (glass, metal, silver, plastic, china)are washed in dishwashing machines. These various materials have to bethoroughly wetted in the final rinse. Rinse aid formulations containingmixed ethers as their only surfactant component meet these requirementsto only a limited extent, if at all, so that the clear-rinse effect ordrying effect is unsatisfactory, particularly in the case of plasticsurfaces.

In addition, only ingredients which are completely biodegradable andtoxicologically safe are now regarded as suitable for use in detergents,including rinse aid formulations. Solventless products are of particularinterest in this regard.

Accordingly, the problem addressed by the present invention was toprovide new ecologically and toxicologically safe formulations whichwould perform as well as conventional formulations and which would nothave any of the disadvantages mentioned above.

DESCRIPTION OF THE INVENTION

The present invention relates to formulations for cleaning hard surfacescontaining

a) mixed ethers corresponding to formula (I): ##STR3## in which R¹ is alinear or branched, aliphatic alkyl and/or alkenyl radical containing 8to 18 carbon atoms, R² is a linear or branched alkyl radical containing1 to 4 carbon atoms or a benzyl radical, m1 has a value of 0 or 1 to 2and n1 has a value of 5 to 15, and

b) fatty alcohol polypropylene glycol/polyethylene glycol etherscorresponding to formula (II): ##STR4## in which R³ is a linear orbranched, aliphatic alkyl and/or alkenyl radical containing 8 to 16carbon atoms, m2 has a value of 0 or 1 to 3 and n2 has a value of 1 to5.

It has surprisingly been found that cleaning formulations, moreparticularly rinse aids, containing mixed ethers and fatty alcoholpolypropylene/polyethylene glycol ethers not only show high ethertoxicological compatibility, they also meet the requirements which acommercial product is expected to satisfy in relation to its performanceproperties.

Another advantage, which is of particular relevance for rinse aids, isthat the preparation of homogeneous, low-viscosity and hence readilydispensable solutions does not require the use of any other, generallyinert solubilizers which make no contribution to drying or theclear-rinse effect, such as for example sodium cumene sulfonate, ethanolor glucose sirup, except in cases where they are needed in smallquantities for the incorporation of dyes and/or fragrances.

Mixed ethers

Mixed ethers are known end-capped fatty alcohol polyglycol ethers whichmay be obtained by relevant methods of preparative organic chemistry.Fatty alcohol polyglycol ethers are preferably reacted with alkylhalides, more particularly butyl or benzyl chloride, in the presence ofbases. Typical examples are mixed ethers corresponding to formula (I),in which R¹ is a technical C_(12/18) or C_(12/14) cocoalkyl radical, m1has a value of 0, n1 has a value of 5 to 10 and R² is a butyl group(Dehypon® LS-54, LS-104, LT-54, LS-104, Henkel KGaA, Dusseldorf, FRG).The use of mixed ethers terminated by butyl or benzyl groups isparticularly preferred for applicational reasons.

Fatty alcohol polypropylene/polyethylene glycol ethers

The polyglycol ethers which form component b) are known nonionicsurfactants which are obtained by addition of propylene oxide and thenethylene oxide or ethylene oxide alone onto fatty alcohols. Typicalexamples are polyglycol ethers corresponding to formula (II) in which R³is an alkyl radical containing 12 to 18 carbon atoms, m2 has a value of0 or 1 and n2 has a value of 2 to 5 (Dehydol® LS-2, LS-4, LS-5, HenkelKGaA, Dusseldorf, FRG). The polyglycol ethers may advantageously have anarrow homolog distribution. In cases such as these, formulationsshowing particularly favorable physical properties are obtained.

The formulations according to the invention may contain components a)and b) in a ratio by weight of 10:90 to 80:20, preferably in a ratio byweight of 30:70 to 70:30 and, more preferably, in a ratio by weight of30:70 to 40:60.

Surfactants, auxiliaries and additives

The formulations according to the invention may contain as furthersurfactants nonionic substances of the alkyl oligoglucoside and/or fattyacid-N-alkyl glucamide type. The most important additives are monobasicand polybasic carboxylic acids, preferably hydroxycarboxylic acids.Typical examples are malic acid (monohydroxysuccinic acid), tartaricacid (dihydroxysuccinic acid); saturated aliphatic dicarboxylic acids,such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipicacid; gluconic acid (hexane pentahydroxy-l-carboxylic acid), butpreferably water-free citric acid. They may be used in quantities ofaround 1 to 50% by weight and are preferably used in quantities ofaround 1 to 30% by weight. Other suitable additives are, above all, dyesand fragrances.

Rinse aid formulations

Typical formulations according to the invention where they are intendedto act as rinse aids may have the following composition for example (ad100% by weight water):

0.5 to 20% by weight mixed ethers,

0.5 to 20% by weight fatty alcohol polypropylene glycol/ polyethyleneglycol ethers and

1 to 50% by weight carboxylic acids.

Formulations containing

3 to 10% by weight mixed ethers

3 to 10% by weight fatty alcohol polyethylene glycol ethers and

1 to 30% by weight citric acid are particularly advantageous.

Commercial applications

The formulations according to the invention contain ecotoxicologicallysafe ingredients, can be formulated without solvents and show excellentwetting power on various materials.

Accordingly, the present invention relates to the use of mixtures ofmixed ethers and fatty alcohol polypropylene glycol/polyethylene glycolethers for the production of formulations for cleaning hard surfaces,more particularly crockery, in which they may be present in quantitiesof 0.5 to 20% by weight and preferably 1 to 10% by weight, based on theformulation. Typical examples of such formulations are, above all, rinseaids, multipurpose cleaners, sanitary cleaners, bottle washingdetergents and generally formulations in which low-foaming surfactantsare normally used.

The following Examples are intended to illustrate the invention withoutlimiting it in any way.

EXAMPLES

I. Surfactants used

A1) C_(12/14) cocofatty alcohol-5 EO-butyl ether Dehypon® LS-54

A2) C_(12/14) cocofatty alcohol-10 EO-butyl ether Dehypon® LS-104

A3) C_(12/18) cocofatty alcohol-10 EO-butyl ether

B1) C_(12/14) cocofatty alcohol 2 EO adduct Dehydol® LS-2

B2) C_(12/14) cocofatty alcohol 4 EO adduct Dehydol® LS-4

B3) C_(12/14) cocofatty alcohol 5 EO adduct Dehydol® LS-5

B4) C_(12/14) cocofatty alcohol 2 PO adduct

B5) 2-Ethylhexyl alcohol 2 EO adduct

B6) C_(12/14) cocofatty alcohol 3 EO adduct (NRE*)

C1) C_(12/14) cocofatty alcohol 5 EO-4 PO adduct Dehydol® LS-54

C2) C_(12/14) cocofatty alcohol 4 EO-5 PO adduct Dehydol® LS-45

All the surfactants are commercial products of Henkel KGaA, Dusseldorf,FRG. Components A and B correspond to the invention while components Cwere used for comparison purposes.

II. Performance testing of the rinse aids

The composition of the surfactant component of the tested rinse aidformulations is shown in Table 1. Mixtures M1 to M6 correspond to theinvention while mixtures M7 to M10 are intended for comparison.

                  TABLE 1                                                         ______________________________________                                        Rinse aid surfactant composition                                              Percentages as % by weight                                                    ______________________________________                                              A1     A2     A3   B1   B2   B3   B4   B5   B6                          M     %      %      %    %    %    %    %    %    %                           ______________________________________                                        M1           30               70                                              M2           50          20   30                                              M3           50                    30   20                                    M4    30                 40        40                                         M5           50          40                  10                               M6                  35                            65                          ______________________________________                                              A1     A2     B1   B2   B3   B4   B5   C1   C2                          M     %      %      %    %    %    %    %    %    %                           ______________________________________                                        M7                                           100                              M8                                                100                         M9           100                                                              M10          30                              70                               ______________________________________                                         Legend: M = Mixture                                                      

a) Foaming behavior of the surfactant mixtures

To determine the foaming behavior of the surfactant mixtures, two eggs(around 100 to 110 g) were diluted with water (16° d) in a ratio of 1:1and stirred for 2 minutes in an electrical mixer. 100 g of the resultingemulsion were then made up to 500 ml with water (16° d) in adouble-walled 2000 ml measuring cylinder and heated to 50° C. After thetest temperature had been reached, 20 g of surfactant mixtures M1 to M9were added to the mixture. By means of a laboratory flow inducer, thesolution was taken in from the bottom of the measuring cylinder througha glass tube. It was returned through a second tube of which the lowerend terminated at the 2000 ml mark of the measuring cylinder. The liquidwas pump-circulated at a rate of 4 1/minute. The volume of the foamformed and the liquid was read off after 5, 10, 20 and 30 minutes. Theresults are set out in Table 2:

                  TABLE 2                                                         ______________________________________                                        Foaming behavior of the surfactant mixtures                                            Volume in ml after mins.                                             Mixture    5      10          20   30                                         ______________________________________                                        M1         750    850         1030 1060                                       M2         720    825         1000 1020                                       M3         710    800          980 1020                                       M4         720    810          900  990                                       M5         600    750         1020 1040                                       M6         700    840          900 1000                                       M7         760    900         1100 1120                                       M8         600    700         1040 1060                                       M9         600    700          900 1000                                       M10        750    920         1100 1120                                       ______________________________________                                    

b) Foaming behavior of the rinse aid formulations

The foam generation of the rinse aid was determined by means of acirculation pressure gauge. The rinse aid (3 ml) was introduced by handduring the final rinse cycle at 50° C. Foaming was evaluated on thefollowing scale:

0 points=no foaming

1 point=slight foaming

2 points=medium foaming (still acceptable)

3 points=vigorous foaming

c) Drying:

15 Minutes after the end of the wash program, the door of thedishwashing machine was fully opened. After 5 minutes, drying wasdetermined by counting the number of droplets remaining on the items ofcrockery listed below. Evaluation:

0 points=more than 5 droplets

1 point=5 droplets

2 points=4 droplets

3 points=3 droplets

4 points=2 droplets

5 points=1 droplet

6 points=no droplets (optimal drying)

d) Clear rinse effect:

After drying had been evaluated, the items of crockery were removed fromdishwashing machine, left to cool for 30 minutes and then visuallyevaluated under light in a black box. The dried residual droplets,streaks, coatings, opaque films etc. left on the crockery and cutlerywere evaluated. Evaluation:

0 points=poor clear rinse effect

8 points=optimal clear rinse effect

e) Performance tests c) and d) were carried out with softened water in aBauknecht GSF 1162 dishwashing machine. The 65° C. normal program wasselected for this purpose. 40 ml of Somat® detergent (Henkel) were addedduring the wash cycle. The quantity of rinse aid was 3 ml and was addedby hand at 50° C. during the final rinse cycle. The water had a saltcontent of 600 to 700 mg/l. Three wash cycles were carried out for eachrinse aid formulation. The following items of crockery were used forevaluating drying and the clear-rinse effect:

6 "Neckar-Becher" glasses (Schott-Zwiesel),

3 "Brasilia" stainless steel knives (WMF),

3 white china dinner plates (Arzberg),

3 red "Valon" plastic dinner plates (Hass mann).

Examples 1 to 5, Comparison Examples C1 to C4

                  TABLE 3                                                         ______________________________________                                        Rinse aids, test results                                                      Percentages as % by weight ad 100% by weight water                                        c (Surfactant)                                                                            CA   FR   St.                                         Ex.  M      %           %    %    °C.                                                                          App.  F                               ______________________________________                                        1    M1     17.5        3.0  0.5  >70   Clear 0                               2    M2     17.5        3.0  0.5  >70   Clear 0                               3    M3     17.5        3.0  0.5  >70   Clear 0                               4    M4     17.5        3.0  0.5  >70   Clear 0                               5    M5     17.5        3.0  0.5  >70   Clear 0                               C1   M6     17.5        3.0  0.5  >75   Clear 1                               C2   M7     17.5        3.0  0.5  >75   Clear 1                               C3   M8     17.5        3.0  0.5  >75   Clear 1                               C4   M9     17.5        3.0  0.5  >75   Clear 1                               ______________________________________                                    

Examples 6 to 10, Comparison Examples C5 to C9

                  TABLE 4                                                         ______________________________________                                        Drying of the items of crockery/clear rinse                                   effect                                                                        Glasses        Knives    China     Plastic                                    Ex.  M.     D      CRE   D    CRE  D    CRE  D    CRE                         ______________________________________                                         6   M1     3.7    6.2   4.1  3.0  5.0  6.3  4.0  5.3                          7   M2     3.5    6.1   4.2  2.9  5.1  6.3  3.9  5.5                          8   M3     3.6    6.2   4.3  3.1  4.8  6.4  4.1  5.3                          9   M4     3.4    6.1   4.4  3.2  4.9  6.4  4.1  5.1                         10   M5     3.3    6.0   4.5  3.1  4.8  6.3  4.0  5.3                         C5   *      4.8    6.0   4.8  6.6  5.0  8.0  5.0  6.8                         C6   M6     2.7    5.7   4.1  2.0  4.9  6.0  4.0  5.3                         C7   M7     2.5    5.8   4.2  1.9  4.0  6.0  4.0  5.1                         C8   M8     1.3    5.3   2.3  1.7  4.0  4.3  2.7  4.5                         C9   M9     2.4    5.8   4.4  2.2  4.9  6.4  4.1  5.1                         ______________________________________                                         Legend:                                                                       D = Drying                                                                    CRE = Clear rinse effect                                                      * = Commercial rinse aid                                                 

We claim:
 1. The process of rinsing a hard surface comprising contactingsaid hard surface with a rinse aid composition consisting essentiallyofa) mixed ethers corresponding to formula (I) ##STR5## in which R¹ is alinear or branched, aliphatic alkyl or alkenyl radical containing 8 to18 carbon atoms, R² is a linear or branched alkyl radical containing 1to 4 carbon atoms or a benzyl radical, m1 has a value of 1 to 2 and n1has a value of 5 to 15, and b) fatty alcohol polypropyleneglycol/polyethylene glycol ethers corresponding to formula (II) ##STR6##in which R³ is a linear or branched, aliphatic alkyl or alkenyl radicalcontaining 8 to 16 carbon atoms, m2 has a value of 1 to 3 and n2 has avalue of 1 to 5, wherein component a) and component b) are present in aweight ratio of 10:90 to 80:20.
 2. A process as in claim 1 wherein saidcomposition consists essentially of 0.5 to 20% by weight of saidcomponent a), 0.5 to 20% by weight of said component b), 1 to 50% byweight of a carboxylic acid, and the balance to 100% of water, allweights being based on the weight of said composition.
 3. A process asin claim 1 wherein R² is a butyl or benzyl group.
 4. The process ofcleaning a hard surface comprising contacting said surface with acomposition consisting essentially ofa) mixed ethers corresponding toformula (I) ##STR7## in which R¹ is a linear or branched, aliphaticalkyl or alkenyl radical containing 8 to 18 carbon atoms, R² is a linearor branched alkyl radical containing 1 to 4 carbon atoms or a benzylradical, m1 has a value of 1 to 2 and n1 has a value of 5 to 15, and b)fatty alcohol polypropylene glycol/polyethylene glycol etherscorresponding to formula (II) ##STR8## in which R³ is a linear orbranched, aliphatic alkyl or alkenyl radical containing 8 to 16 carbonatoms, m2 has a value of 1 to 3 and n2 has a value of 1 to 5, whereincomponent a) and component b) are present in a weight ratio of 10:90 to80:20.
 5. A process as in claim 4 wherein said composition consistsessentially of 0.5 to 20% by weight of said component a), 0.5 to 20% byweight of said component b), 1 to 50% by weight of a carboxylic acid,and the balance to 100% of water, all weights being based on the weightof said composition.
 6. A process as in claim 4 wherein R² is a butyl orbenzyl group.